The universality that helped humans conquer the world appeared very early in our evolutionary history, according to sediments and stone tools from the Olduvai Gorge in Tanzania.
Olduvai has provided some of the oldest known instruments and fossils of our kind, Homo. Recent studies that show evidence of the environment buried in the sediment. The results show that our early relatives were equipped to adapt to a new environment about 2 million years ago.
This seems to have been a key ability that allowed our relatives to become global. 1
Maybe they managed to prepare for it just by staying in one place in Africa. In Ewass Oldupa, a recently excavated site on the edge of the famous Olduvai Gorge, findings show that early hominins lived in an ever-changing landscape.
Life after the volcano
The oldest evidence we have of early human relatives in the Olduvai Gorge is a handful of stone tools made and used about 2.03 million years ago.
Like the other instruments found at Ewass Oldupa, they are part of the Olduwan complex: relatively simple stone tools made from early hominins such as H. erectus and H. habilis. Olduwan tools are mostly sharp scales and many basic tools for cutting, scraping and punching. They are much less complex and precise than tools made by later hominins, such as Neanderthals, who cut small scales from carefully prepared stone cores. But for several hundred thousand years, Olduwan’s rough tools did the trick.
At Ewass Oldupa, the job was to survive in a landscape of mostly raw fern meadows dotted with a few grasses and woody plants watered by a meandering river. Ferns were probably the first plants to take root on top of a wide pumice stone fan that had erupted from a nearby volcano not long before. Traces of this landscape are still buried in a layer of sediment about a meter above the rocky remains of the ancient pyroclastic flow; paleoanthropologist Michael Petraglia of the Max Planck Institute for the Study of Human History and colleagues found fossilized pollen and microscopic pieces of fossilized plant tissue called phytoliths in the layer, along with 10 stone tools.
For hunter-gatherers like H. habilis, whose fossils have been found just a few hundred meters from Evas Oldupa, the fernil pool would be a pretty good place to live.
The river offered easy access to water, and the area’s geology provided several sources of stone for tools. Geochemical analysis of the instruments at Ewass Oldupa suggests that hominins here collected some of their quartzite locally and dared to stay up to 12 kilometers (7.5 miles) away. They seem to choose different materials – in some cases as specific as choosing slightly different types of quartzite from different protrusions – for specific instruments. (A study from last year also suggests that the earliest instrument makers in our family tree knew enough to choose their materials wisely.)
But then, as always, everything changed.
New worlds in the same place
Thousands of years later, the hominins who once invaded the banks of the river would not recognize the landscape around Evas Oldupa. The breccias’ meadows had given way to a pile of forests and pastures around the lake’s shores. The microscopic fossils trapped in the sediment suggest that the plant species that make up these forests and lawns often change, and charcoal deposits reveal that forest fires periodically cover the area, helping to rearrange the landscape.
At other points in the long prehistory of the area, the lake is expanding, and the muddy sediments on the shore of the lake suggest a lush landscape of forests and palm groves. Later, the shore of the lake gave way to a dry steppe, mostly bare by trees and grass. Each of these environments offered wildly different foods, water, supplies, and challenges, but hominins seemed to keep coming back to Evas Oldupa.
“Over time, these habitats sometimes change slowly or quickly,” Petraglia told Ars. “It’s hard to see how quickly hominins have entered new ecosystems thanks to the recording resolution, but it’s clear they’ve managed to cope with a wide variety of environments.”
Petraglia and his colleagues found stone tools left by hominins who lived on the site (probably H. habilis) excludes and includes constant change over its 200,000 years. The 565 stone tools, scattered for thousands of years by layered sediments on the site, do not look like the detritus of a permanent settlement. Instead, hominins appear to have left the pool several times, perhaps due to a sudden change in the environment or volcanic eruptions, but they have returned.
“There have been a number of volcanic events over 235,000 years that are represented in Ewass Oldupa,” Petraglia told Ars. “Interestingly, hominins returned to these areas after each of the eruptions – that is, they never left the region entirely.”
Jack of all trades
And even if the earliest hunters and gatherers in Evas Oldupa were to find later versions of the site, completely foreign, they would still recognize the tools people used to survive it. For about 200,000 years, hominins relied on the same basic tools to deal with trapped meadows by the river, pieces of forest and pasture, the lush shore of the lake and the dry steppe.
Olduvan’s tools for chopping, scraping, and striking were relatively simple, but they were also incredibly flexible. According to Petraglia and his colleagues, Olduwan technology offers a basic, common set of tools that work as well in a palm grove by the lake as in a dry steppe. People have conquered the world because we are universalists, and generalists can adapt to almost anything. Our early relatives obviously had the same advantage.
Nature Communications, 2020 DOI: 10.1038 / s41467-020-20176 (For DOI).